Is there a way to run upgrade.php for one blog?

WP CLI has a command that can upgrade the database:

wp core update-db

If that command doesn’t upgrade the entire network, you can pass in the site you want upgraded as an additional parameter

e.g.

wp core update-db --site="http://example.com/testsite/"

You can get WP CLI from here:

http://wp-cli.org

it’s also available on github

You can install using:

curl -L https://raw.github.com/wp-cli/builds/gh-pages/phar/wp-cli.phar > wp-cli.phar

It also comes with VVV